Stresses and strains on the motor/electrical cord junction are a common problem due to various external forces exerted on the electrical power supply cord. If the motor falls while plugged-in or the user pulls on the cord to move the motor, stress on the junction could lead to the electrical cord pulling out of the motor, thereby breaking the junction. This may lead to a dangerous short and will require costly repairs involving disassembly of the motor.
It is known to provide mechanisms for relieving stresses and strains exerted on the motor/electrical cord junction. One conventional mechanism is a cable connector clamp that can be inserted into an opening in the motor housing. The clamp includes a cylindrical housing that defines a passage for an insulated electrical cord. Within the housing, there is a resiliently deflectable clamping element that permits insertion of the cord from the external side of the motor housing, but prevents extraction, and thereby eliminates any stress or strain at the motor/electrical cord junction due to external forces on the cord. An example of this type of clamp is disclosed in U.S. Pat. No. 4,970,350 issued Nov. 13, 1990. A variation of this clamp is disclosed in U.S. Pat. No. 5,594,209 issued Jan. 14, 1997.
It is also known to design the motor such that the housing comprises multiple components which, when assembled, work in conjunction to provide strain relief for the electrical cord passing therethrough. In one example, the housing includes a main portion which has a slot defining one half of an opening for the electrical cord. A removable portion of the housing has a slot defining another half of the opening. With the cord in place, the removable portion is inserted into the main portion and screws are used to secure the housing components together. Once the housing is secured, the electrical cord is constrained within the opening, which has a diameter that is smaller than the diameter of the cord. The edges of the opening continuously squeeze the cord and prevent movement. An example of this design is disclosed in U.S. Pat. No. 3,207,837 issued Sep. 21, 1965.
Other mechanisms incorporate conduit box covers or various other clamping devices which are typically fastened to the housing using screws.